With the increase in terrorist events in the United States, the need for effective security systems to sense intrusion into secured areas has greatly increased. For instance, a security system for the protection of a vast system of underground utilities accessed by manholes with removeable covers is needed. A highly effective system to detect entrance into these underground spaces and utilities is needed in order to protect against vandalization and terrorist activities within these spaces and the spaces to which these underground utilities lead. Heretofore, it has been known to use fiber optic sensors to detect theft of articles, intrusion into protected areas, as well as a variety of other purposes.
In another instance, a security system that is able to encompass remote areas and can be monitored from a remote location is needed. Typically, security systems for secured locations involve an outer security fence to protect an outer perimeter of a secured area. An inner fence protects the actual secured location against unauthorized entry. The area between the pair of fences is monitored constantly via motion sensors and motion sensitive cameras among other sensors. The pair of fences is traditionally located close to the secured location. Thus, once someone has breached the second of the pair of fences, they are close to the secured location. Thus, the area within which the security force has to intercept this person is very limited. It would be far more advantageous to allow notification of an attempted breach of the secured location from a greater distance than provided by the traditional setup known in the current state of the art.
The prior art security systems and sensors require a physical connection between the optic fiber and the moveable member, and also require electrical power at the location sought to be protected making them less useful for many security applications, including wide geographical area systems. More importantly, no provision is made for identifying the location of an intrusion event where large numbers of sensors are utilized.
Optical time-domain distance reflectometer (OTDR) devices are used to maintain fiber optic communication systems. For example, the OTDR may be used to sense a fiber breakage, water seepage, irregular bends, or other defects in one or more optical fibers of the fiber communication network along the routing path of the network. In large municipalities it is not uncommon for there to be a thousand miles of fibers in an optical fiber network.